Impact of serpentine length and capillary diameter on graphite exfoliation with sonication-enhanced microfluidization

This study explores the influence of serpentine length (1 to 12 m) and capillary diameter (1.40 to 0.59 mm) in a microfluidization process, enhanced by low-power sonication and a constant operating pressure of 600 bar, for producing highly conductive exfoliated graphite thin films. Optimal exfoliation was achieved with a serpentine length of 12 m and a capillary diameter of 0.59 mm, yielding nanographite flakes with a peak thickness of approximately 27.5 nm—a significant reduction compared to the control nanographite with a thickness of 235.8 nm. The quality of the nanomaterial evaluated by SEM, Raman spectroscopy, profilometry, AFM, XRD, and FTIR analysis. The microfluidic process minimally impacts the lateral size of micrographite, decreasing the lateral size peak position from 3.93 μm for the control graphite to 2.41 μm for the exfoliated graphite. Then, suspensions of these nanographite flakes was used to develop flexible and highly conductive films with electrical conductivity of 0.0019 Ω.cm. Finally, a mechanism has been postulated to explain the process of graphite exfoliation through sonication-enhanced microfluidization.